Method of producing aggregates from earth substances



Patented May 2, 1933 j? I E-D- T mm a. amass, or onrcaao, nlLmoIs METHOD or raonucms Aeeanearnsraom EAnTHsUBsTA cEs I I No Drawing. 7 -Applicat1oi1 filed April 8,

My invention has to dowith the production of light-weight aggregates made from molten materials such as slags produced in metallurgical, industrial or boiler furnaces.

I 5 In my prior Patent No. 1,538,482, I have disclosed and broadly claimed an improved process of producing hard cellular aggreg'atesof clay or earth substances,.the terms clay. and earth-substances being therein used in avery broad sense, stated in the specification of saidpatent.

I have found that the method of production of these aggregates may be further im- 1 provedby melting-minerals or earth-sub stances prior [to sintering the aggregate forming'mass. The melting of minerals by themselves for that primary purpose only is; an expensive step, but I have found that the slags, which are the by-products of v smelting processes'afli'ord a particularly ad .vantageous material for my presentprocess. I have been particularly successful inproducing a very high grade'aggregate; from blastffurnace slag, which is the fused product containing the" gangue of the iron ores, the limestone flux and the coke ash, incldent to the manufacture of iron. Such slag has hitherto been treated as waste or worse, in that there 1s considerable expense-1n carting it away or otherwise disposing of the same.

The iron-ore, limestone and coke are mixed in the blast furnace in such proportions as to give a slagof nearly uniform analysis, and this uniformity is'of value in producing my aggregate.

I differs from that of most natural argillace- I Tous or clayey materials in thatits base is lime 40 and magnesia, offwhich substances it contains about one-half'of its total weight; of alumina it generally contains about-15% (fifteen per cent)i and of silica around 35% (thirty-five per cent) Inthe natural materials, on the other hand, silica is the chief constituent. Iron blast furnace slags, par-j ticularly those issuing from normal blast furnace: operations in the production of basic, "Bessemer," or foundry iron, are very 5o suitable formy purpose. As .these slags flowlinfthe liquid state fromthe blast fur- The composition ofblast furnace slag process is carried out, in accordance with the 1932. Serial No, 604,120.; c.

nace I cause them granulated by mix- 1 ing a stream of water under pressurewith the "liquid slag, orby dropping the liquid 'slaginto azbody of Water, or by using other 4 cooling and granulated means such as air, or a combination'of air and water, or mechanical means of gr'anulating, all 'ofwhich are known in the art. The granulatedslag f is porous and cellular and when properly granulated is of a very light weight 'char- 'acter." This is important in that in the subsequent-heat treating process to which I subject it, the material is more readily fused and produces a more uniform product and a product of light-weight, since the original volume of cells is largely preserved. The granulated, slag in itself is sufficiently'light-wei'ght to make aggregate, but the walls ofthe'cells are very friable. There'- fore in order to make a strong aggregate I crush the larger particles of granulated slag to convenient size to mix intimately with fuel, but not so fine as to destroy th'e'cellula'r structure of-the small'particles; and then subjectit to, a second fusing or heat treatment, whichstrengthens the cell walls, and fuses'the slag particles together. I preferablyuse the heat treatment process described inmyPate'nt s -1,538,482. I have: found by that methodofheat treatment, I" can sinter more uniformly and more economically with a smaller amount of fuel per ton of product i and a'lesser cost ofoperation than in kilns.

From the foregoing it will be understood that, the initial steps in'the improved process consist in melting the mineral substances, incooling and in granulating or crushing the same to desired size. When this improved process of my prior patent, above identified,

r the melted minerals or slags are granulated and are commingled with finely divided fuel and preferably with' dissimilar mineral substances, such as clays, shales, fluxes, etc. and water or other liquid, suchas tar refuse or the like, to moisten'the substances. This I commingled mass in uniformly-and freely permeable condition is spread in a relatively thin stratum upon a pervious supporter or d grate. Then the fuel in the commingled mass broadly considered, by other operations, such as the rip-drafting sintering process and by the use of the rotary kiln, which, though less eflicient, may in some instances serve the particular purpose, especially where use may be made of existing equipment.

I have found by extensive experimentation that I can vary the quality of my product by mixing umnolten materials with the granulated slag. By mixing up to 20% (twenty per cent) of earthly material, such as slatery coal mine refuse, with granulated slag and the necessary fuel, I can produce an aggregate which is lighter in Weight than many other similar aggregates which are produced by sintering raw unmolten materials. I11 some cases it may be advantageous to mix larger percentages of umnolten materials with the slag, the percentages depending not only on the-quality desired but also on the cost of assembly of the materials.

While my experiments have been largely conducted with blast furnace slags in which the bases, lime, magnesia, soda and potash, formed approximately one-half of the weight, I have found that slags with a higher or lower silica or alumina content than is present in ordinary blast furnace slag, also can be treated successfully by my process, providing they are derived from a melting operation which caused them to be completely molten prior to granulating or crushing, and sinterin g. I therefore do not limit myself to theslags from iron blast furnaces, but. may use slags from open hearth furnaces which run higher in lime and magnesia or I may mix blast furnace and open hearth slags in their granulated or crushed form and sinter them together or I may use slags from copper or lead or other metallurgical furnaces or boiler furnaces by themselves or mixed with other slags or mineral substances.

What I claim is:

1. The rocess of. producing from earth minerals a light-weigl1t cellular mass suitable for concrete aggregates and like purposes, which consists in melting earth minerals, cooling and granulating the resulting slagand thereafter commingling the granulated slag with finely divided fuel, and sintering the same.

2. The process of producing from earth minerals a light-Weight cellular mass suitable for concrete aggregates and like purposes, which consists in melting earth minerals, cooling and granulating the resulting slag and thereafter commingling the granulated slag with finely divided fuel and with a finely divided dissimilar substance that has not been melted, and then sintering the commingled mass.

3. The process of producing from earth minerals a light-weight cellular mass suitable for concrete aggregates and like puring it by mixing it with fuel and downdrafting the mixture.

6. The method of producing light aggregate from molten slag which consists in mixing the slag with unmolten materials and sintering the mixture.

7. The method of producing light aggregate which consists in granulating molten ulating and crushing the slag and then fusinc slags, mixing with them other materials of unlike chemical composition and sintering the mixture.

8. The method of producing light aggregate which consists in melting minerals, cooling and breaking up the resulting slag, mixing with it fuel and mineral substances of different chemical composition, and sintering the mixture by the down-draft process.

9. The process of producing from slag resuiting as a waste by-product in the reduction of metallic ores, a light-weight cellular material suitable for'concrete aggregates and like purposes, which consists in granulating the same. commingling the granulated slag with finely divided fuel, in maintaining the commingled mass in uniformly and freely permeable condition and igniting the fuel of the mass at one surface thereof, and in concurrently maintaining three actions, to

wit: (a) progressively burning out the fuel of the mass by forcing a combustion-supporting gas therethrough; (b) maintaining the commingled mass in a state-of quiescence, free from mechanical agitation; and (a) cooling that portion of the mass from which the fuel particles have been burned by forc- :mingled mass in uniformly and freely pering the combustion-supporting gas therethrough on its way to theburning zone.

10. The process of producingfrom slag resulting as a waste by-product 1n the reduction of metallic ores, a light-weight cellular materialsuitable for concrete aggregates and like purposes, which consists in granulating the same, commingling thefgranulated slag with finely divided fuel and with finely divided earth substances, in maintainin the commingled'mass in uniformly and reely permeable condition and igniting the fuel of the mass at onesurfacethereof, and in con-v currently maintaining three actions, to wit: (a) progressively burning out thefuel of the mass by forcing a combustion-supporting gas therethrough; (b) maintaining, the. commingled mass in a state of quiescence, free from mechanical agitation; and (a) cooling that portion of the mass from which the fuel particles have been burned by forcing the combustion-supporting gas therethrough on I 7 its way to the burnin zone.

11. The process of producing from slag resulting as a waste by-product in the reduction of metallic ores, a light-weight cellu lar material suitable for concrete aggregates and like purposes, which consists in granulating the same, commingling the granulated slag with finely dividedfuel and finely di vided earth substances, and moistening the commingled mass, 111 maintalmng the commeable condition and igniting the fuel of the mass at one surface thereof, and in concurrently maintaining three actions, to wit: (a)

progressively burning out the fuel of the mass by forcing a combustion-supporting gas therethrough; (b) maintaining the commingled mass in a state of quiescence, free from mechanical agitation; and (0) cooling that portion of the mass from which the fuel particles have been burned by forcing the combustiomsupporting gas therethrough on its way to the burning zone.)

FRANK A. GLASS;

In testimony whereof I aflix my signature. I 

